Method of making a foundry mold and casting



Feb. 24, 1970 v PAOL] 3,496,989

METHOD OF MAKING A FOUNDRY MOLD AND CASTING Filed June '7. 1.967

INVENTOR Angelo Puoli FIG. 3 Y RONALD E. BARRY Attorney United States Patent US. Cl. 164-30 2 Claims ABSTRACT OF THE DISCLOSURE A foundry mold having a heat collapsible refractory core retained in position in the mold by cellular plastic chaplets. The use of cellular plastic chaplets also contemplates the use of cellular plastic patterns with the cores embedded in the pattern.

The use of cores in casting is well known. These cores are selected as to size and precisely located in order to assure an accurate production of the article to be cast. Since the core is generally lighter, often substantially lighter, than the metal to be cast there is a tendency for the' core to rise while the metal is being poured. In order to hold the cores in proper position metal chaplets are placed or secured to the core to prevent the core from moving before the molten metal fills the mold cavity. The chaplet head must be designed to prevent the head from sinking into the sand of the core as a result of the buoyant force of the core acting on the chaplet.

Chaplets presently being used must be made of a metal which is compatible with the metal being cast. This usually means the chaplet must be made of the same metal being cast. Chaplets are, therefore, premade in large numbers of metallic material similar to the material being cast and then stored until used. However, most metals rust if they are not properly protected and a rust preventative is added to the surface of the chaplet after it has been manufactured. This involves a further step in the manufacture of the chaplet and also added costs.

The primary object of the present invention is to provide a new and improved method for supporting a core within a foundry mold.

Another object of the present invention is to provide a simple system for locating chaplets on a core in a mold.

A still further object of the present invention is to provide a chaplet for supporting a core that is easy to locate and can be readily adjusted to different heights in a mold.

Another object of the present invention is to provide a chaplet that can be used with any metal that is to be cast.

A still further object of the present invention is to provide a low cost, easy to store type chaplet.

Another object of the present invention is to provide a method for locating a core in a mold.

A still further object is to provide an improved core for a foundry mold.

Another object of the present invention is to provide a preformed pattern for a foundry mold which has the core embedded within the pattern.

Another object of the present invention is to prevent a rupture in the casting wall due to blows or cold shuts using a metal chaplet.

These objects are accomplished by either embedding the core in a cellular plastic pattern which has the shape of the article to be cast or securing cellular plastic blocks having the required dimensions to the surfaces of the core. The cellular plastic material must be vaporizable or gasifiable without any substantial residue at the temperature of the molten casting charge. The core may be made of conventional materials or can be made with a cellular plastic center coated with a refractory material which remains solid at the temperature of the molten casting charge. Regardless of the type of core used, it can be either located in a preformed cavity in the mold forming material and held in position by the chaplets or it can be embedded in the pattern material.

Other objects and advantages will become more readily apparent from the following detailed description when read in connection with the accompanying drawings in which:

FIG. 1 is a side view of a core shown mounted in a mold with a gasifiable chaplet located on the top.

FIG. 2 is a view taken on line 22 of FIG. 1.

FIG. 3 is a view of a core embedded in a pattern prior to being embedded in the mold forming material.

Referring to the drawing, a mold 10 is shown formed from a cope 12 and a drag 14 positioned on a mold board 16 and held together by screws or clamps 18. A cavity 20 is shown formed within a conventional casting sand 22 by the insertion and withdrawal of a pattern (not shown). An ingate 24 is connected to the bottom of the cavity and a splash basin 26 is provided at the top of the ingate. The formation of this type of mold is well known and needs no further explanation.

Prior to securing the cope on the drag a core 28 is positioned within the cavity in the drag. The core is located within the cavity also in a conventional manner. Chaplets 30 are located on the top of the core. These chaplets are made of cellular plastic material, such as polystyrene or polyurethane, and are secured to the top of the core. A small amount of adhesive can be used to secure the chaplet to the core. The cha lets can be preformed or cut to the required dimensions, however, preformed chaplets assure closer dimensions. If it is considered necessary a vent locator depression 32 and a vent wire 34 may be embedded in the cope when the cavity is formed therein to provide a vent for the gases formed on decomposition of the chaplet.

Cores presently used in foundry molds are of the heat collapsible type in which a silica sand is held together with a heat destructible binder. These cores collapse when exposed to the heat of the molten casting charge due to the break down of the binder. An alternate form of core which can be used in the present invention comprises a core made with a cellular plastic center 36 covered with a coating material 38. The cellular plastic material may be foamed polystyrene or polyurethane of a density suificient to provide support for the refractory material until the molten material sets. The coating material can consist of gypsum, clay, silica, calcium oxide or similar material which is applied to the outer surface of the foamed plastic center to a thickness sutficient to remain solid upon contact with a molten casting charge and to retard the flow of heat to the cellular plastic material.

Another alternate form of this invention is to preform a pattern 40 of cellular plastic material as described in Shroyer Patent No. 2,830,343 but to include a core 42 in the pattern (FIG. 3). This can be done by foaming the plastic material in a mold having the required dimensions with the core located in the mold so that it is embedded within the pattern. The pattern and core can then be embedded in any type of mold forming material, such as conventional foundry sand. If the pattern is coated with a refractory material loose free flowing material such as sand, metalshot or the like can be used as the mold forming material.

This latter technique automatically locates the core in the mold and eliminates the necessity of using chaplets since the pattern material above the core will hold it in position. This technique has also been found feasible to mass produce similar articles where cores are to be used. The patterns with the cores embedded therein can be simply placed in a fiask, embedded in mold forming material to be replaced by the molten casting charge.

Although only a few embodiments of the present invention have been shown and described it should be apparent that various changes and modifications can be made herein without departing from the scope of the appended claims.

What is claimed is:

1. In a method of casting comprising the steps of forming a cavity in a mold-forming material to the shape of an article to be cast, inserting and supporting at least one core in said cavity in a position to provide a recess within the article to be cast and spaced from the upper surface of said cavity, 1

forming a member of a cellular plastic material that is gasifiable substantially without residue on subjection to the heat of a molten casting charge and shaped to fit in and partially fill the gap between the upper surface of said core and the upper surface of the cavity directly above said core,

placing the thus formed member in said space between the upper surfaces of said core and cavity and in engagement therewith to prevent the upward movement of the core as a result of the buoyant forces of the molten metal during the pouring of the molten casting charge, and pouring a molten casting charge into said cavity at a location spaced from said member.

2. The method of claim 1 including the step of providing vent openings in the mold-forming material above said member.

References Cited UNITED STATES PATENTS 3,037,252 6/1962 House et a1 16441OX 3,189,958 6/1965 Newbold 1641 12 3,374,827 3/1968 Schebler 164l37 3,374,824- 3/1968 Snelling 164-246 X I. SPENCER OVERHOLSER, Primary Examiner ROBERT D. BALDWIN, Assistant Examiner US. Cl. X.R. 164-137 

